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.\" Common Development and Distribution License ("CDDL"), version 1.0.
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.\" 1.0 of the CDDL.
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.\" Copyright 2015 Joyent, Inc.
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.Dd July 30, 2024
.Dt PR_FCNTL 3PROC
.Os
.Sh NAME
.Nm pr_fcntl
.Nd inject fcntl system call into victim process
.Sh LIBRARY
.Lb libproc
.Sh SYNOPSIS
.In libproc.h
.Ft int
.Fo pr_fcntl
.Fa "struct ps_prochandle *P"
.Fa "int fd"
.Fa "int cmd"
.Fa "void *argp0"
.Fa "void *argp1"
.Fc
.Sh DESCRIPTION
The
.Fn pr_fcntl
function injects the
.Xr fcntl 2
system call into the target process
.Fa P
by means of the agent LWP.
If the process handle
.Fa P
is
.Dv NULL
then this is equivalent to calling
.Xr fcntl 2
on the currently running process.
.Pp
The arguments
.Fa fd
and
.Fa cmd
have the same meaning as in
.Xr fcntl 2 .
The value of
.Fa cmd
determines how many arguments are passed.
A command that takes no arguments, like
.Dv F_GETFD ,
should pass both
.Fa argp0
and
.Fa argp1
as
.Dv NULL .
A command that takes integer arguments, like
.Dv F_SETFL
or
.Dv F_DUP3FD ,
should cast the integer arguments to a
.Fa "void *"
and pass unused arguments as
.Dv NULL .
See
.Xr fcntl 2
for the full description and purpose of the
system call and its arguments.
.Pp
The
.Fn pr_fcntl
function only works on active processes.
Process handles that correspond to core files, zombie processes, or ELF objects
do not support system call injection.
.Sh RETURN VALUES
Upon successful completion, the
.Fn pr_fcntl
function's return value is that described in
.Xr fcntl 2 .
Otherwise,
.Sy -1
is returned and
.Sy errno
is set to
.Er ENOSYS
to indicate that the system call could not be injected.
.Sh ERRORS
For the full list of errors see the
.Sy ERRORS
section in
.Xr fcntl 2 .
.Pp
The
.Fn pr_fcntl
function will fail if:
.Bl -tag -width Er
.It Er ENOSYS
An error occurred while trying to invoke the agent LWP and inject a
system call in the process handle
.Fa P
or the process handle
.Fa P
does not support system call injection.
.El
.Sh INTERFACE STABILITY
.Sy Uncommitted
.Sh MT-LEVEL
See
.Sy LOCKING
in
.Xr libproc 3LIB .
.Sh SEE ALSO
.Xr fcntl 2 ,
.Xr libproc 3LIB ,
.Xr proc 5